Feed-regulator for grlnding-mills



(No Model.)

M. B.'GHUROH.

FEED REGULATOR FOR GRINDING MILLS.

Patented June1-3, 1882.

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Uwrraa ramps MELVIN B. CHURCH, OF GRAND RAPIDS, MICHIGAN.

FEED-REGULATOR FOR GRINDING-MILLS.

SPECIFICATION forming part of Letters Patent No. 259,490, dated June 13, 1882.

Application filed October '7, 1881. (No model.) I

To all whom it may concern Be it known that I, MELVIN B. CHURCH, of Grand Rapids, in the county of Kent and State of Michigan, have invented a new and useful Improvementin Feed-Regulators for Grinding- Mills; and I do hereby declare that the following is a full, clear, and exact description of the same.

My invention relates to feeding devices for grinding-mills. It is specially designed for that class of mills which are used for regrinding plaster, but is capable of wider application, and may be used in connection with other mills for grinding other materials.

The object of the invention is to obtain perfeet uniformity of feed for any given speed of the stone and an automatic regulation of the feed with any variationin the set speed, whereby the material is delivered to the stone faster or slower in exact proportion as the stones move at a higher or lower rate of speed.

The accompanying drawing illustrates my invention in the form in which I have embodied it, the figure representing a longitudinal vertical section of the apparatus.

This apparatus is specially designed for regrindin g plaster. This materiahbei'ore regrinding, when large quantities of it are placed in the garner or hopper, will, as is well understood, tend to pack in proportion to the weight of the mass, and this packing interferes materially with the regularity of the feed. It cannot be made to flow regularly and uniformly by the use of any ordinary devices, and will not feed at all or with any certainty by its own weight.

Various devices have been heretofore usedfor this and like purposes; but I have found after much experiment that an absolutely positive feed is essential for this and like material when it is to be fed to stones for regrinding. For producing such positive feed I use the ordinary screw, but cover a part thereof with a closely-fitted case, and leave the other part exposed in the mass of the material, since I have found by experiment that the screw, to produce uniform and regular feed, must work in and be surrounded by the material in such a manner that the exposed part of the screw shall be pressed upon at every point by the material to be fed.

The nature of my invention is fully set forth hereinafter in connection with parts well known in the art, and the particular part which constitutes my invention is specified in the claims.

In the drawing, A represents the garner, capable of holding a sufficient quantity of the plaster or other material. At its bottom, where the sloping sides unite, is placeda throat or passage, (0, provided with a valve, b. This passage a opens into another chamber, B, which Iprefer to make about two feet long, fourteeninches wide, and twelve inches high. The diameter of the throat a is about eight or ten inches. These proportions are not essential, and may be varied; but I have found them well adapted to the purpose. It will be understood that the material passes by its own weight through the throat a and fills the chamber B. In the bottom of this chamber I place a screw or auger, cl, supported in suitable bearin gs and extending the entire length of the chamber. Over about half the length of this screw or anger I place a covering, f, which incloses the auger from the chamber closely about the sides, but is open at both ends. The open end within the box receives the material, which is carried along by the screw into the covering or case], and is delivered by the same motion at the outer end into an open pipe, g, leading to the stones. About one-half of the screw not thus closely covered is constantly in contact with the plaster or other material, and as the screw works in this mass it works constantly full, and a uniform movement of the screw fitting closely in case f carries a uniform amount through such case and delivers it to the stone. The case f fits closely to the screw and 0011- tains none of the feed except that carried along by the screw. It therefore compels the screw to act uniformly and evenly, and prevents it from crowding the mass into the delivery end of the chamber; but as the stone is constantly varying in speed it is necessary to vary the rate of movement of the screw. This 1 accomplish by extending the shaft or shank of the screw outside the chamber, and providing it with an ordinary cone-pulley, E, connected by a band to a like reverse pulley, F, the shaft of which is suitably connected to any convenient part of the mechanism which drives the stone.

The feed may be regulated in relation to any given speed of the stone by adjustmentof the band upon the cone-pulleys. After such adjustment it will be plain that variation of the speed of the stone will directly vary the speed of the screw, and thereby the amount of feed. In some cases it may be practicable to deliver into the garner uniformly and constantly the material to be reground. In such cases the density of the material in the bottom of the garner would be practically uniform, and the screw might be located in the bottom of the garner and the lower chamber be omitted.

The screw must still be arranged with the last half uncovered in the same manner as heretofore described. This construction, in fact, would be no more than a substitution of another feeding device, instead of the garner, and such a feeding device need not be accurately uniform, but should deliver with sufficient regularity to keep the exposed part of the screw always surrounded by the material.

ample, in the patent of Lowell, No. 229,722, of 1880.

Having described my invention, I claim 1. In a grinding-mill, a garner, a chamber, B, below the garner, a throat leading from the garner to said chamber, a feed-screw located in said chamber, properly driven, and having a close case covering it at the discharge end, said case leaving about one-half of the screw uncovered and exposed to contact with the material fed to the chamber, all the parts being combined substantially as described.

2. The combination of the screw d, the box or chamber containing the material to be fed, the casing f, open at both ends, and covering only part of the screw, as described, and suitable driving mechanism connected to that driving the stone, as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

MELVIN B. CHURCH.

Witnesses:

L. W. SEELY, F. L. MIDDLETON. 

